There have been a lot of epoxy woes on the board lately, so here is one solution that has not popped up before. The pic below shows a twin-tube epoxy dispenser that works like a caulking gun. Pressure on the handle preloads the spring, so you can squeeze and release and it continues to dispense until you thumb the release lever. The business end is a static mixing tube, so the product is ready for use right out of the tip. The plastic plug is removed from the twin tubes, the threaded collar is reused around the mixer, and the gun is ready for use. The static mixers are available in a wide range of sizes and lengths; the small one in the pic (6" x 1/4") is fine for low-viscosity unfilled resins such as those used in boatbuilding. Any size batch can be dispensed, and the partially used tubes can be recapped for future use. The static mixers may be reuseable, but I always toss them. Assuming that the tubes are loaded properly, the system is goof proof. The tubes are available in bulk, empty, and you fill them with whatever you use, epoxy, urethane, vinyl ester, or whatever. If the product needs to be thickened, it is best to
dispense the mixed product into a separate container and then add the thickener. The tubes come in 1:1, 2:1, 4:1 and 10:1 ratios, so most products can be made to work. The last batch of tubes for this tool cost $2.50 each or so, the static mixers are about $1.50, and the gun was +/- $100 when I bought it in '92. All system components are available from ConProTec in New England, and other similar systems are available elsewhere (a quick internet search should turn up some others). This is not a cheap solution, but it certainly is effective; you can put exactly as much as you want exactly where you want in no time flat, with no worries about mixing and metering.